C ++数组分配 [英] C++ Array Allocation

问题描述

你好，

给出以下声明:

Hello,

Given the following declarations:

<br />
size_t const ARRAY_ROWS = 2000000000; // 2,000,000,000<br />
typedef double DoubleArray_T[ARRAY_ROWS];<br />
<br />
...<br />
<br />
int main(void)<br />
{<br />
    DoubleArray_T * A1;<br />
}<br />

如何分配数组?

我尝试过:

How can I allocate the array?

I''ve tried:

<br />
	A1 = new DoubleArray_T;<br />

会有人友好地让我偶尔通过即时消息问他们C ++问题吗?

如果可以的话，肯定会有所帮助...

Would anyone be kind enough to let me ask them C++ questions occasionally through Instant Messaging?

Sure would be helpful if I could...

推荐答案

如果您真的想分配2,000,000,000个双精度数组，为什么不直接这样做呢?

If you really want to allocate an array of 2,000,000,000 doubles why not just do it directly?

double *A1 = new double[ ARRAY_SIZE ];

如果要使用一个明确命名的大对象bin，请使用typedef并使用

If you want to have a distinctly named large object bin the typedef and use

struct DoubleArray_T
{
    double data[ ARRAY_SIZE ];
};

DoubleArray_T *A1 = new DoubleArray_T;

反而.这使得数组的行为比typedef更像对象.请记住，typedef仅引入了另一种类型的别名，并且除非您知道自己在做什么，否则指向数组的指针(如DoubleArray_T *在代码中一样)是真正的怪兽.在您的原始代码中，new DoubleArray_T返回一个指向double的指针，而您试图将其分配给DoubleArray_T *，这是不同的类型.

干杯，

灰

PS:经过编辑，使其看起来至少是英语

instead. This makes the array behave more like an object than the typedef does. Remember a typedef only introduces an alias for another type and that pointers to arrays (as DoubleArray_T * was in your code) are really strange beasts unless you know what you''re doing. In your original code new DoubleArray_T was returning a pointer to a double and you were trying to assign that to a DoubleArray_T *, which are different types.

Cheers,

Ash

PS: Edited to make it at least look English

您真的要分配几乎16 GB 吗?
:)

Do you really want to allocate almost 16 GB?
:)

我找到了一种方法.

这行得通，但我不喜欢它:
A1 = new DoubleArray_T[1];

还有别的办法吗?
绝对不建议使用硬编码的值.
一定有更好的方法...

I''ve found a way.

This works, but I don''t like it:
A1 = new DoubleArray_T[1];

Isn''t there another way?
Using hard-coded values is never recommended.
There must be a better way...

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